Structures and Functions of Membrane Antenna Proteins with High Resolution Solution and Solid State NMR

本研究的主要目的是建立高分辨溶液核磁共振与固体核磁共振相结合的方法来阐明膜蛋白和色素复合物的结构和功能。对于研究的目标，我们选择了细菌的膜天线，和叶绿体anntena之一。膜天线LH 1（light harvesting complex 1）或B870含有由两个多肽（α和β）和两个细菌叶绿素分子组成的亚基（B820）作为辅基。我们已经建立了使用选择性同位素富集样品来阐明假体组周围结构的方法。因此，我们用同位素富集的BCh 1a和正常亚基，或同位素富集的α和天然β亚基和天然BCh 1a重构LH 1的亚基B820，并利用这些样品通过溶液NMR解析结构。在这种情况下，富含^<13>C的色素细菌叶绿素和富含^2H的蛋白质可以聚焦细菌叶绿素和环境的信号。因此，我们对这些样品广泛使用多维NMR。这些研究揭示了利用核磁共振技术解析膜蛋白的方法。LH 1的整个单元，即，B870分子太大，不能用溶液核磁共振研究，我们试图充分利用固体高分辨核磁共振来观察其核磁共振谱。所获得的数据进行了分析方面的知识的解决方案NMR。指定的信号告诉我们，B870将由在溶液状态下具有相似结构的亚基组成。多维溶液核磁共振和同位素富集技术为确定组分A和R多肽在氯仿/甲醇溶液中的结构提供了方法

Main object of the research is to establish the method to elucidate structures and functions of membrane proteins and pigment complexes in terms of high resolution solution nuclear magnetic resonance in conjunction with solid state NMR. For the target of the studies we have selected one of the bacterial membrane antenna, and chlorosome anntena. The membrane antenna called LH1 (light harvesting complex 1) or B870 has subunits (B820) composed of two (α and β) polypeptides and two bacteriochlorophyll molecultes in the active site as the prothetic groups. We have established the methods to elucidate the structures around the prothetic group with use of selectively isotope enriched samples. Thus, we reconstituted the subunit B820 of the LH1 with the isotope enrichied BCh1 a and the normal subumits, or the isotope enriched a and the natural β subunit and the natural BChl a and could resolve the structures with use these samples by the solution NMR. In this case the ^<13>C enriched pigment bacteriochlorophylls and the ^2H enriched proteins could focus the signal of the bacteriochlorophylls and the environment. Futhermore we have make extensive use of multidimensional NMR with these samples. These studies have disclosed the method to elucidate membrane proteins in terms of NMR. The whole unit of LH1, i.e., B870 is too large to be investigated by the solution NMR, we have tried to observe the NMR in full use of solid high resolution NMR. The obtained data have been analyzed in terms of the knowledge of the solution NMR. The assigned signal tells us the B870 would be composed of the subunits with similar structures in the solution states. The multi-dimensional solution NMR and the isotope enrichment have afforded the method to clarify the structure of the component a and R polypeptide in the chloroform/methanol solution